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According to this link, the distance between the inside, stationary disc pad and the disc brake rotor should be twice the distance between the rotor and the outside, moving disc pad.

Why should the stationary disc pad be further away from the rotor than the moving disc pad? From what I understand, the rotor flexes towards the stationary disc pad when you brake. Wouldn't increasing the former distance increase the amount of flex? Is that desirable? Would it not cause unnecessary strain on the rotor?

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    I had never heard that before and always adjusted mine the other way around. After a quick Googling, I was surprised to find that Park Tools gives the same advice. They don't mention why though. :/
    – jimchristie ♦
    Mar 29, 2017 at 18:33
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    The amount of rotor flex is small and not a concern. I am not clear on why all manufactures seem to suggest that the stationary disc pad be further away, so I am interested to see the answers. Perhaps it has to do with clearing debris (the floating caliper can be forcibly pushed in a bit if it encounters debris and/or a warped rotor). The stationary rotor, is well stationary, so it could be safer to give it as much clearance as possible.
    – Rider_X
    Mar 29, 2017 at 19:23
  • I also wonder if it has to do with improving brake modulation (preventing the on/off brake feel). Either way it is an interesting question.
    – Rider_X
    Mar 29, 2017 at 21:08
  • I wish the answer was still there. Until I see some reasoning behind that counter intuitive advice, I am not buying it.
    – Deleted User
    Mar 29, 2017 at 21:42
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    I am not. I am guessing that perhaps someone came up with that idea and it was just perpetrated around sites by tech writers borrowing from other sources. I've found it in three places, but no explanation for it in any of them. I have heard an explanation of "closer to the non-moving pad so less rotor flex" from many mechanics during my time. I have a hard time accepting counter intuitive instruction with no reasoning. I would guess it was just a copy and paste error and nothing malicious.
    – Deleted User
    Mar 29, 2017 at 22:04

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SRAM's brake setup instructions for BB7 brakes (select user manual from the service documents, step 10 in the user manual) specify that the inboard/fixed pad should be further from the rotor than the outboard/moving pad. The ParkTool instructions that @jimirings links in their comment are specific to this model of brake and repeat the manufacturers instructions in this regard.

Other manufacturers provide different advice, for example Tektro's instructions for their mechanical disk brakes (TRP Online Resources - select "All Spyre and Spyke models" from the road disc subheading under the user manuals section, Tektro Mechanical Disk Brake Owner's Manual, or Tektro Support > Download - select "Mechanical Disk Brake - User Guide") specify that the brake pads should be evenly spaced on both sides of the rotor. The Montague blog you've linked to use a Tektro Novella brake but repeat the instructions given by SRAM, not what Tektro recommend.

Neither manufacturer give any reason for the specific alignment, the only reference I could find was the following section from CX Magazine's article How to: Set Up & Adjust Mechanical Disk Brakes:

Now look through the caliper. The rotor should be sitting center in the gap or slightly to the outboard side. This should position the inboard pad into the gap.

This inboard pad position should be one of your greatest priorities. If the inboard pad is too far out, when you hit the brake, the outboard pad will clamp the rotor against the caliper instead of the brake pad.

The pictures included make it clear that the caliper housing should be slightly offset to ensure that as the fixed inboard pad wears and the rotor flexes it does not contact the caliper housing itself. This would lead to damage to the rotor and/or the caliper.

You should probably still follow the manufacturers recommendations for your given brake model, however aligning the caliper to have more space on the fixed side then aligning the pads evenly would also be suitable if you are unable to find specific instructions from your manufacturer.

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    TRP mechanical brakes have two floating calipers, which might be the reason behind the different recommendation. Nice summary. So the take home is that the extra gap on the inboard (fixed pad) ensure the inboard pad comes out farther from the caliper body which helps reduce the chance the rotor touching the caliper body due to wear. If one constantly checks pad wear and adjusts, the difference in gaps may not matter as much.
    – Rider_X
    Mar 30, 2017 at 19:59

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